Physiology Exam 2 Chapter 8

Match the type of signal to its description a) graded potential b) action potential c) both

In the membrane of a resting nerve cell, when chemically gated Cl- channels open

When more action potentials arrive at the axon terminal, how are neurotransmitters affected?

Information coming into the CNS is transmitted along ____ neurons

The small space between the sending neuron and the receiving neuron is the

A molecule that carries information across a synaptic cleft is a

When calcium ions enter the synaptic terminal,

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron,

If a signal from a sending neuron makes the receiving neuron more negative inside,

When voltage-gated K+ channels of a resting neuron open,

The primary problem in hyperkalemia is

Conduction occurs along an axon because

A stronger stimulus to a neuron results in ________.

At a(n) ________ synapse, a neurotransmitter is released to affect the postsynaptic cell.

Which of the following would NOT cause the membrane potential to change from -70 mV to +30 mV?

The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called

Which of the following describes a similarity between graded potentials and action potentials?

Graded potentials can

In a graded potential, what is the effect of cytoplasmic resistance and current leak?

What type of conduction takes place in unmyelinated axons?

An action potential is self-regenerating because __________.

Why does regeneration of the action potential occur in one direction, rather than in two directions?

What is the function of the myelin sheath?

What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?

In which type of axon will velocity of action potential conduction be the fastest?

The following are steps involved in transmission at the cholinergic synapse: 1. Chemically regulated ion channels on the postsynaptic membrane are activated. 2. Calcium ions enter the axon terminal. 3. An action potential depolarizes the axon terminal at the presynaptic membrane. 4. Acetylcholine is released from storage vesicles by exocytosis. 5. Acetylcholine binds to receptors on the postsynaptic membrane.

Action potentials are primarily associated with the membranes of

A home satellite dish receives signals from a satellite, allowing your television to display TV shows. Which part of a neuron is analogous to the satellite dish?

In a(n) ________ synapse, there is a direct physical connection between cells.

During childhood, growth and development of the brain PRIMARILY occurs by increasing

How is an action potential propagated along an axon?

Why does the action potential only move away from the cell body?

The velocity of the action potential is fastest in which of the following axons?

Nerve cells in the central nervous system are primarily

The cells that we are capable of controlling consciously are the _____ neurons.

Somatic motor neurons control

When two or more graded potentials arrive at the trigger zone, which of the following could happen?

Where in the neuron is an action potential initially generated?

The depolarization phase of an action potential results from the opening of which channels?

The repolarization phase of an action potential results from __________.

Hyperpolarization results from __________.

What is the magnitude (amplitude) of an action potential?

What would happen to the membrane potential if a resting cell suddenly becomes more permeable to Na+?

Neurotransmitters are usually released into synapses by __________.

What would the sudden increase in axonal permeability to sodium cause?

Glial cells

If a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes arrive at the trigger zone at the same time, what is most likely to occur?

Where do most action potentials originate?

What opens first in response to a threshold stimulus?

What characterizes depolarization, the first phase of the action potential?

What characterizes repolarization, the second phase of the action potential?

What event triggers the generation of an action potential?

What is the first change to occur in response to a threshold stimulus?

An excitatory postsynaptic potential (EPSP)

In a synapse, neurotransmitters are stored in vesicles located in the __________.

An action potential releases neurotransmitter from a neuron by opening which of the following channels?

Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane.

Binding of the neurotransmitter to its receptor causes the membrane to __________.

The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned?

In order for a synapse to be an effective means of cellular communication, slow removal or inactivation of neurotransmitter molecules from the synapse is important.

The total amount of neurotransmitter released at the axon terminal is directly related to

The rearrangement of connections at synapses, which occurs throughout life, is termed

The ion necessary to initiate the release of acetylcholine into the synaptic cleft is

The pattern of synaptic connectivity where a large number of presynaptic neurons provide input to a single postsynaptic neuron, is known as

Inhibitory postsynaptic potentials (IPSPs )

Neurotransmitter is stored and released from

When comparing action potentials to graded potentials, an/two important distinguishing characteristic/s is/are

The addition of stimuli arriving in rapid succession to produce an action potential is called ________ summation.

The rising phase of the action potential is due to

Which ion(s) is/are higher in concentration inside the cell compared to outside?

Excitatory neurotransmitters of the CNS usually act by opening ________ channels.

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?

What stops the rising phase of the action potential?

In order to signal a stronger stimulus, action potentials become

The addition of several stimuli arriving from different locations on the same cell to produce an action potential is called ________ summation.

A chemical synapse USUALLY includes ________. 1. axon terminal 2. presynaptic cell 3. synaptic cleft 4. postsynaptic cell 5. dendrite

If the sodium-potassium pumps in the cell membrane of a neuron fail to function, over time

Repair of damaged neurons can be assisted by certain neurotrophic factors secreted by the

To increase the amount of neurotransmitter released onto a postsynaptic cell, the presynaptic cell would have to

A ________ is a compound that influences a postsynaptic cell's response to a neurotransmitter.

Which of the following will best increase the conduction rate of action potentials?

Which type of receptor would bind acetylcholine and be found in skeletal muscle?

Which characteristic of channels is determined by the gating state of the channel?

When voltage-gated Na+ channels of a resting neuron open,

The all-or-none principle states that

The region where the axon terminal meets its target cell is called the

Which glial cells form myelin in the central nervous system?

Myelin is formed by

The axon is connected to the cell body by the

Which of the following statements best describes the concept of permeability? Choose the best answer.

The two cells below are hypothetical cells with a concentration of 100 mOsm of K+ inside the cells and containing only leak channels for K+ within the membrane. Each cell is placed into a different solution containing different concentrations of K+ in the extracellular fluid. Which of the two cells below has a higher permeability to K+ and why?

Which of the following statements best describes the resting membrane potential? Choose the best answer.

Sodium (Na+) ions are more concentrated on the outside of the cell, this would result in diffusion of the ion into the cell. 2. Potassium (K+) ions are more concentrated on the inside of the cell, this would result in diffusion of the ion out of the cell.

The gaps between adjacent Schwann cells on an axon are called

During the relative refractory period, an initial threshold-level depolarization is usually not sufficient to trigger an action potential. Why?

Choose all of the items that are incorrectly matched.

Which type of synapse is most prevalent in the nervous system?

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.

During depolarization, which gradient(s) move(s) Na+ into the cell?

What is the value for the resting membrane potential for most neurons?

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

The concentrations of which two ions are highest outside the cell.

Which of the following is the most common location where action potentials originate?

The absolute refractory period of an action potential

The potential difference across a membrane or other barrier is a measure of the ________ across the barrier.

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference?

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you?

The plasma membrane is much more permeable to K+ than to Na+. Why?

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors.

What prevents the Na+ and K+ gradients from dissipating?

All of the following must occur before a second action potential can begin, EXCEPT

Which two properties determine the conduction velocity in a mammalian neuron?

A. graded potential B. action potential C. both originate(s) at the trigger zone

How would the absolute refractory period be affected if voltage-gated sodium channels remained inactivated?

When sodium channels open during an action potential, the opening is caused by

The falling phase of the action potential is due primarily to

A damaged neuron has a better chance of survival and repair if the ________ is/are undamaged.

Clusters of nerve cell bodies in the peripheral nervous system are called

The part of the neuron that receives most of the incoming signals is the __________.

The all-or-none principle states that